Senior Backend Engineer (Infrastructure)

Location: 100% Remote (Poland)Contract: B2B (via Entrada AI Poland)ABOUT ENTRADA AIEntrada AI is a specialized consulting partner and a strategic portfolio company of Databricks Ventures. This is a rare distinction: Databricks invested in us because of our technical excellence, placing us in the 'inner circle' of the ecosystem. For our engineers, this means direct access to product roadmaps, private previews, and the teams building the platform.You will join a team of industry veterans and Databricks MVPs. We look for engineers who value clean architecture over quick fixes. We don't just maintain pipelines; we solve complex architectural challenges for Fortune 500 clients using features often before they are widely available.The Role:You'll be joining the team as a backend engineer responsible for architecting and owning the core platform powering the predictive intelligence system. This includes authentication, metering, AI pipeline orchestration, and billing. You'll work directly with leadership and influence every major technical decision.What You'll Own:- Authentication & Identity: Firebase Auth, SSO foundations, tenant/user modeling, tier-based feature gating- RCA Engine: Vertex AI/Gemini integration, prompt engineering, structured response parsing, high-performance request routing- Storage & Data Layer: Redis for ephemeral RCA storage, DuckDB + Kafka (Pub/Sub on GCP) for persistent data, Cloud SQL + pgvector for embeddings- Quota & Usage Management: Monthly RCA limits, trial tracking, enforcement logic, upgrade triggers- Billing & Subscriptions: Stripe integration, webhooks, lifecycle automation, tier transitions- Observability & Reliability: Logging, metrics, tracing, error tracking, audit logs, health checksYou Should HaveRequired:- 4+ years backend engineering experience (Python or Node.js preferred)- Production RESTful API experience- Hands-on GCP services experience (Cloud Run, BigQuery, Cloud SQL, or equivalents)- LLM API integration and tuning experience (Vertex AI, OpenAI, Anthropic, etc.)- Stripe (or similar) billing/subscription integration experience- End-to-end system ownership in fast-moving teams- Strong debugging, performance tuning, and reliability engineering fundamentalsNice to Have:- Firebase Authentication (or equivalent identity platforms)- Redis for caching or ephemeral data- Apache Iceberg, data lakes, or multi-tier storage design- Freemium/tiered SaaS product experienceTHE OFFERCompetitive Salary: 160-180/hStart: ASAPStable Employment: Contract signed with our Polish entity (Entrada AI Poland).100% Remote: Full flexibility to work from anywhere in Poland.Apple Hardware: Macbook Air M4 15' provided.Referral Bonus: Bonus for bringing other top-tier engineers to the team.Professional GrowthRECRUITMENT PROCESSIntroductory Call (20 min): Short conversation with our Recruiter to discuss your background and expectations.Technical Interview (60 min): Deep dive into your technical skills with our engineering team.Optional Client Interview: Required only in specific cases.Decision & Offer: We aim to close the process efficiently.